1. Field of the Invention
The present invention relates to a vehicle control apparatus for use with electric motor driven wheels, such as in an electric motor four-wheel drive vehicle, wherein an internal combustion engine drives one pair of wheels among the front and rear wheels, and the motive power from an electric motor appropriately drives the other pair of wheels via a clutch. More particularly, the present invention relates to an apparatus that discriminates the rotational direction and controls the drive of the electric motor-driven wheels.
2. Background Information
A hybrid four-wheel drive vehicle is disclosed in Japanese Laid Open Patent Application No. 2002-218605, is in which a pair of electric motor driven wheels are appropriately driven by the motive power from an electric motor via a clutch. This vehicle drives the front or rear wheels by an internal combustion engine, and the rear or front wheels are capable of being driven by an electric motor via a clutch, wherein the electric motor is directly driven by the electrical power from a four-wheel drive specialized generator that is coupled to and driven by the internal combustion engine.
In summary, the hybrid four-wheel drive is enabled by generating electrical power by applying a load to the generator of a magnitude up to the point where the wheels driven by the engine are about to undergo acceleration slippage, or applying a load to the generator corresponding to just the surplus torque portion of the engine when acceleration slippage has occurred; driving the electric motor by the electric power generated thereby, and at that time transmitting to the electric motor driven wheels the motive power from the electric motor via the clutch, which has been engaged.
Basically, leaving the clutch in a released state when not in four-wheel drive avoids a decline in fuel economy by ensuring that the electric motor driven wheels do not excessively pull on the electric motor. However, the clutch is left in an engaged state because it is preferable to shift to a four-wheel drive state due to the significant risk that the engine driven wheels will experience acceleration slippage when starting from a stop.
When starting from a stop, a load is applied to the generator corresponding to the amount that the accelerator pedal is depressed, thereby generating electric power. That generated electric power drives the electric motor, and the vehicle is thereby started from a stop in a four-wheel drive state.
In view of the above, it will be apparent to those skilled in the art from this disclosure that there exists a need for an improved vehicle control apparatus. This invention addresses this need in the art as well as other needs, which will become apparent to those skilled in the art from this disclosure.